4,586 research outputs found
Applying Abstract Argumentation Theory to Cooperative Game Theory
We apply ideas from abstract argumentation theory to study cooperative game
theory. Building on Dung's results in his seminal paper, we further the
correspondence between Dung's four argumentation semantics and solution
concepts in cooperative game theory by showing that complete extensions (the
grounded extension) correspond to Roth's subsolutions (respectively, the
supercore). We then investigate the relationship between well-founded
argumentation frameworks and convex games, where in each case the semantics
(respectively, solution concepts) coincide; we prove that three-player convex
games do not in general have well-founded argumentation frameworks.Comment: 15 pages, 1 tabl
Strategic Argumentation is NP-Complete
In this paper we study the complexity of strategic argumentation for dialogue
games. A dialogue game is a 2-player game where the parties play arguments. We
show how to model dialogue games in a skeptical, non-monotonic formalism, and
we show that the problem of deciding what move (set of rules) to play at each
turn is an NP-complete problem
Abstract Games of Argumentation Strategy and Game-Theoretical Argument Strength
We define a generic notion of abstract games of argumentation strategy for (attack-only and bipolar) argumentation frameworks, which are zero-sum games whereby two players put forward sets of arguments and get a reward for their combined choices. The value of these games, in the classical game-theoretic sense, can be used to define measures of (quantitative) game-theoretic strength of arguments, which are different depending on whether either or both players have an “agenda” (i.e. an argument they want to be accepted). We show that this general scheme captures as a special instance a previous proposal in the literature (single agenda, attack-only frameworks), and seamlessly supports the definition of a spectrum of novel measures of game-theoretic strength where both players have an agenda and/or bipolar frameworks are considered. We then discuss the applicability of these instances of game-theoretic strength in different contexts and analyse their basic properties
A game-theoretic perspective on the notion of argument strength in abstract argumentation
This paper is concerned with the problem of quantifying the strength of arguments in controversial debates, which we model as abstract argumentation frameworks [Dung, 1995]. Standard approaches to abstract argumentation provide only a qualitative account of the status of arguments, whereas numerical measures of argument strength might provide a more precise evaluation of their individual status. Intuitively, the strength of an argument in a debate essentially depends on how a proponent of that argument would defend himself against the criticisms of someone opposed to the argument. Since there can be many ways of defending and attacking an opinion, we essentially conceive argument strength as an equilibrium resulting from the interactions taking place between the opinions that a proponent and an opponent of the argument could a priori embrace. More formally, we define argument strength in terms of the value of a repeated two-person zero-sum strategic game with imperfect information. Then, using the game-theoretic properties of such games and notably the von Neumann minimax theorem [Neumann, 1928], we establish and illustrate the main properties of this new argument strength measure
A Comparative Study of Ranking-based Semantics for Abstract Argumentation
Argumentation is a process of evaluating and comparing a set of arguments. A
way to compare them consists in using a ranking-based semantics which
rank-order arguments from the most to the least acceptable ones. Recently, a
number of such semantics have been proposed independently, often associated
with some desirable properties. However, there is no comparative study which
takes a broader perspective. This is what we propose in this work. We provide a
general comparison of all these semantics with respect to the proposed
properties. That allows to underline the differences of behavior between the
existing semantics.Comment: Proceedings of the 30th AAAI Conference on Artificial Intelligence
(AAAI-2016), Feb 2016, Phoenix, United State
Stratified Labelings for Abstract Argumentation
We introduce stratified labelings as a novel semantical approach to abstract
argumentation frameworks. Compared to standard labelings, stratified labelings
provide a more fine-grained assessment of the controversiality of arguments
using ranks instead of the usual labels in, out, and undecided. We relate the
framework of stratified labelings to conditional logic and, in particular, to
the System Z ranking functions
Analysis of Dialogical Argumentation via Finite State Machines
Dialogical argumentation is an important cognitive activity by which agents
exchange arguments and counterarguments as part of some process such as
discussion, debate, persuasion and negotiation. Whilst numerous formal systems
have been proposed, there is a lack of frameworks for implementing and
evaluating these proposals. First-order executable logic has been proposed as a
general framework for specifying and analysing dialogical argumentation. In
this paper, we investigate how we can implement systems for dialogical
argumentation using propositional executable logic. Our approach is to present
and evaluate an algorithm that generates a finite state machine that reflects a
propositional executable logic specification for a dialogical argumentation
together with an initial state. We also consider how the finite state machines
can be analysed, with the minimax strategy being used as an illustration of the
kinds of empirical analysis that can be undertaken.Comment: 10 page
Coalitional games for abstract argumentation
International audienceIn this work we address the issue of the uncertainty faced by a user participating in multiagent debate. We propose a way to compute the relative relevance of arguments for such a user, by merging the classical argumentation framework proposed in [5] into a game theoretic coalitional setting, where the worth of a collection of arguments (opinions) can be seen as the combination of the information concerning the defeat relation and the preferences over arguments of a " user ". Via a property-driven approach, we show that the Shapley value [15] for coalitional games defined over an argumentation framework, can be applied to resume all the information about the worth of opinions into an attribution of relevance for the single arguments. We also prove that, for a large family of (coalitional) argumentation frameworks, the Shapley value can be easily computed
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